Electronic article security systems for detecting and preventing theft or unauthorized removal of articles or goods from retail establishments and/or other facilities, such as libraries, are well known and widely used. In general, such security systems employ a label or security tag which is affixed to, associated with, or otherwise secured to an article or item to be protected or its packaging. Security tags may take on many different sizes, shapes, and forms, depending on the particular type of security system in use, the type and size of the article, etc. In general, such security systems are employed for detecting the presence of an active security tag as the security tag (attached to the protected article) passes through a security or surveillance zone or passes by or near a security checkpoint or surveillance station.
Certain prior art security tags work primarily with radio frequency (RF) electromagnetic field disturbance sensing electronic security systems, such as, but not limited to those disclosed in U.S. Pat. No. 3,810,147 entitled "Electronic Security System", U.S. Pat. No. 3,863,244 entitled "Electronic Security System Having Improved Noise Discrimination", and U.S. Pat. No. 5,276,431 entitled "Security Tag For Use With Article Having Inherent Capacitance", and their commercially available implementations and counterparts. Such electronic security systems generally establish an electromagnetic field in a controlled area through which articles must pass when being removed from the controlled premises. A tag having a resonant circuit is attached to each article, and the presence of the resonant circuit in the controlled area is sensed by a receiving system to denote the unauthorized removal of an article. The resonant circuit can be deactivated, detuned, shielded, or removed by authorized personnel from any article authorized (i.e. purchased or checked out) to be removed from the premises, thereby permitting passage of the article through the controlled area without alarm activation.
Security tags can be affixed to or associated with the article being secured or protected in variety of manners. Removal of a tag which is affixed to an article can be difficult and time consuming and, in some cases, requires additional removal equipment and/or specialized training. Detuning the security tag, for instance, by covering it with a special shielding device such as a metallized sticker, is also time consuming and inefficient. Furthermore, both of these deactivation methods require the security tag to be identifiable and accessible, which prohibits the use of tags embedded within merchandise at undisclosed locations or tags concealed in or upon the packaging.
Systems are known for the remote electronic deactivation of a resonant tag circuit where the deactivated tag can remain with an article properly leaving the premises. Electronic deactivation of a resonant security tag involves changing or destroying the detection frequency resonance so that the security tag is no longer detected as an active security tag by the security system. There are many methods available for achieving electronic deactivation, such as the systems shown in U.S. Pat. Nos. 3,624,631 and 3,810,147, in which a fusible link in the resonant circuit is burned out by the application of energy higher than that employed for detection to either activate or deactivate the tuned circuit. Deactivation may also be accomplished by shorting the tag's resonant circuit. Such electronically deactivateable tags include a weak link created by forming a dimple in the tag which brings more closely together plates of a capacitor formed by the metallizations of two different parts of the tag's resonant circuit on opposite sides of the tag substrate, thereby allowing electrical breakdown at moderate power levels. Such a breakdown causes a short circuit between the two metallizations. This type of deactivateable tag can be conveniently deactivated at a checkout counter or other such location by being momentarily placed above or near a deactivation device which subjects the tag to electromagnetic energy at a power level sufficient to cause one or more components of the security tag's resonant circuit to either short circuit or open, depending upon the detailed structure of the tag.
The demand for tags which may be installed at the point of manufacture by the manufacturer, as opposed to at the point of sale by the retailer, has increased rapidly. As such, the use of such tags is a growing trend. Since such tags are easily hidden within an article, it is important to provide other and/or additional means and methods for deactivating such tags. Thus, there is a need to provide a security tag which can be deactivated by other means or methods. The present invention fulfills this need by providing a tag which includes a novel means for disabling the resonant circuit of the tag.